What is the recommended dose of penicillin (Penicillin V) for treating strep (streptococcal) pharyngitis in pediatric patients?

Penicillin Dosing for Pediatric Streptococcal Pharyngitis

For pediatric streptococcal pharyngitis, the recommended dose of oral penicillin V is 250 mg two to three times daily for 10 days. 1

First-Line Treatment Options

Oral Therapy

• Penicillin V (first choice):

  • Children: 250 mg 2-3 times daily for 10 days 2, 1
  • Adolescents: 250 mg 4 times daily or 500 mg twice daily for 10 days 2

• Amoxicillin (alternative first-line):

  • 50 mg/kg once daily (maximum 1000 mg) for 10 days, OR
  • 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 2, 1
  • Note: Amoxicillin has been shown to be as effective as penicillin V in treating streptococcal pharyngitis 3

Injectable Option

• Benzathine Penicillin G (intramuscular):
  • For patients with poor adherence or inability to take oral medications
  • <27 kg (60 lbs): 600,000 units as a single dose
  • ≥27 kg (60 lbs): 1,200,000 units as a single dose 2, 1, 4

Alternative Treatments for Penicillin-Allergic Patients

For patients with penicillin allergy, the following alternatives are recommended:

• Non-anaphylactic allergy (no immediate hypersensitivity):

  • Cephalexin: 20 mg/kg/dose twice daily (max = 500 mg/dose) for 10 days 2
  • Cefadroxil: 30 mg/kg once daily (max = 1 g) for 10 days 2

• Anaphylactic allergy:

  • Clindamycin: 7 mg/kg/dose 3 times daily (max = 300 mg/dose) for 10 days 2, 1
  • Azithromycin: 12 mg/kg once daily (max = 500 mg) for 5 days 2, 1
  • Clarithromycin: 7.5 mg/kg/dose twice daily (max = 250 mg/dose) for 10 days 2, 1

Important Clinical Considerations

• Treatment Duration: A full 10-day course is essential for most antibiotics (except azithromycin which is 5 days) to maximize pharyngeal eradication of GAS and prevent complications such as acute rheumatic fever 1

• Timing: Patients are considered non-contagious after 24 hours of antibiotic therapy, with symptoms typically improving within 24-48 hours after starting treatment 1

• Compliance: Complete the full course even if symptoms resolve quickly to prevent complications and recurrence 1

Common Pitfalls and Caveats

1. Inadequate Treatment Duration: Shorter courses may lead to treatment failure and increased risk of complications like acute rheumatic fever. Always complete the full 10-day course (5 days for azithromycin) 1

2. Macrolide Resistance: Be aware that up to 5% of GAS in the US shows resistance to macrolides like azithromycin and clarithromycin 1

3. Carrier State: GAS carriers (asymptomatic individuals with positive throat cultures) generally do not require antimicrobial therapy as they are unlikely to spread GAS pharyngitis and are at minimal risk for developing complications 2, 1

4. Tonsillectomy: Not recommended solely to reduce the frequency of GAS pharyngitis 2

5. Treatment Failure: If symptoms persist or worsen after 5 days of appropriate treatment, consider non-compliance, penicillin treatment failure, new infection, or viral pharyngitis in a streptococcal carrier 1

Penicillin remains the drug of choice for streptococcal pharyngitis due to its proven efficacy, safety profile, narrow antimicrobial spectrum, low cost, and no documented resistance from Group A Streptococcus 1.